For patients and their intimate partners, cancer poses significant physical and emotional challenges that can negatively impact both individuals and the couple as a whole. Accumulating evidence suggests that couples' ability to communicate effectively, or lack thereof, plays a major role in the psychological adjustment of both individuals and the quality of their relationship. Two key conceptual models have been proposed to account for how communication difficulties lead to poorer outcomes: the social-cognitive processing model and the relationship intimacy model. These models posit different mechanisms and processes affecting outcomes, and thus have substantially different implications for intervention. To date, however, there has been little empirical examination of the mechanisms proposed by each model, limiting advancement of the science as well as the development of theory-based interventions. The purpose of the proposed project is to test and compare the utility of these models using comprehensive and methodologically rigorous methods. The project is guided by a dyadic perspective that includes examination of both patient and partner perceptions and behaviors in communicating their cancer-related concerns and responding to one other. We propose a longitudinal multi- method approach to examining communication processes including: (a) standard self-report questionnaires assessing process and outcome variables collected at multiple time points over the course of one year; (b) ecological momentary assessments (EMA) to sample participant reports in real time; and (c) laboratory-based couple conversations from which we will derive observational measures of communication behavior and vocal indices of emotional arousal. The proposed methodology will address limitations of previous research including cross-sectional designs and a sole reliance on self-report measures. The targeted sample includes a total of 434 patients with advanced breast or colorectal cancer and their partners. The aims of the study are: (1) to examine the overall fit of the social-cognitive processing and relationship intimacy models in explaining patient and partner psychological and relationship adjustment as they occur on a day-to-day basis and over the course of one year; (2) to examine the fit of the models for different subgroups (males versus females, and patients versus partners); and (3) to examine the utility of the various methods of assessing communication (self-report questionnaires versus EMA versus observational measures) by examining the degree to which baseline indices from these different measurement strategies predict adjustment at one-year follow up. Findings from this study have the potential to advance relationship science and our understanding of the processes through which interpersonal communication affects patient and partner adaptation to cancer. Our long-term goal is to use the results to inform theory, measurement, and the design and implementation of efficacious interventions aimed at optimizing both patient and partner well-being.